Semiconductor devices are used in a large number of electronic devices, such as computer, communication, consumer electronics, cars and others. Semiconductor devices comprise integrated circuits (ICs) that are formed on semiconductor wafers by depositing many types of thin films of material over the semiconductor wafers, and patterning the thin films of material to form the integrated circuits. The most common active element in the ICs is transistor including planar field-effect transistors (FETs) such as metal oxide semiconductor (MOS) transistors and 3D fin field-effect transistors (FinFETs).
In the integrated circuit, a trench isolation structure is frequently used to separate and insulate two active areas in a semiconductor device. The trench isolation structure is typically formed by recessing a substrate, overfilling a dielectric material therein, and performing a planarization process thereof. However, precisely controlling a planarization depth and adequately maintaining the structure stability between the trench isolation structure and adjacent structures are still a challenge.